Power factor call the indicator characterizing distortions of a form of current and tension of the power supply network. It is caused by influence of loading, and its increase leads to increase of active power and decrease in losses from useless circulation of reactive energy.
Power factor of electrical units
On value of this coefficient it is possible to judge how the receiver uses source power. At its increase when active power is constant, chain current decreases, power losses in wires also decrease that provides a possibility of additional loading of a source. When loading remains invariable, increase in this coefficient leads to increase of active power.
If power factor is equal to unit, it means that reactive power is equal to zero, at the same time all power of a source is considered active. Active resistance is characteristic of electric lamps, at their inclusion the shift of a phase between current and tension is almost absent therefore for lighting loading the power factor can be considered equal to unit. At standard industrial loading power factor - 0.8, at computer — 0.7. For engines of alternating current this indicator depends on loading, at their underloading the power factor sharply falls.
Ways of increase in power factor
Power factor can be increased in different ways. One of the most widespread — turning on of the special device which is called the compensator, parallel to receivers of electric energy. As such device most often use the battery of condensers. In this case the compensator is static. This way of increase is called compensation of shift of phases or compensation of reactive power. If the compensator is absent, from a source to the receiver the current which lags behind tension on a certain angle of shift of phases arrives. When the compensator is connected, on it there passes the current advancing tension at the same time in a source chain the angle of shift of phases concerning tension will be less. For full compensation of an angle of shift of phases it is necessary to create conditions that current of the compensator was equal to a reactive component of current of a source. At turning on of the compensator the source and an electrical network unload from reactive energy as it begins to circulate on a chain the receiver compensator. Synchronous electrical machines can be also used to increase in power factor, then call the compensator rotating. At the same time the efficiency of use of electrical networks and generators of alternating current increases and also losses, arising from useless circulation of reactive energy between the receiver and a source decrease.